An alternative to the more commonly grown Empress or Foxglove tree, is Paulownia kawakamii also known as the Sapphire Dragon Tree - Paulownia kawakamii is a very fast growing deciduous tree to around 10-12m tall from Taiwan and Eastern China, and parts of Japan, where it is considered endangered.
When young it has enormous heart-shaped 5-lobed leaves that are velvety soft to the touch on both surfaces. The large round brown flower buds form in the autumn and are held conspicuously on the bare branches until they burst forth just prior to the foliage in the spring. The individual pale lilac-blue flowers are 30-50mm wide in long, erect, terminal panicles.
Paulownia is a genus of around 15 deciduous Asian trees that have in the past been placed in either (Scrophulariaceae) the Figwort family or the Bignonia family (Bignoniaceae) but more recently taxonomists have put in its own family, the Paulowniaceae.
Plant in full sun in any good soil. Prune while young to desired form after which little attention is required. Paulownia do loose the very soft part of the young growth during the winter, but the tree is ultimately very hardy, and for the first few years is exceedingly vigorous.